Bug fixes from Crash2Burn and ActiveQuery limit by j03m

Hi - we noticed that under extreme load closures from pending requests to memcached were adding up in mem and would eventually crash the node process. On our end it was better to implement a queue limit and log the overages to splunk for tracking (thus know we needed more servers) then to allow the process crash to happen. 

You can view usage is examples/queue_limit.js

This also contains Crash2Burns submitted bug fixes. (we work together, I pulled his changes into my fork which we're using right now.)

Let me know what you think.